Predicting the Peritoneal Absorption of Icodextrin in Rats and Humans Including the Effect of α-Amylase Activity in Dialysate

♦ Background:

Contrary to ultrafiltration, the three-pore model predictions of icodextrin absorption from the peritoneal cavity have not yet been reported likely, in part, due to difficulties in estimating the degradation of glucose-polymer chains by α-amylase activity in dialysate. We incorporated this degradation process in a modified three-pore model of peritoneal transport to predict ultrafiltration and icodextrin absorption simultaneously in rats and humans.

♦ Methods:

Separate three-pore models were constructed for humans and rats. The model for humans was adapted from PD Adequest 2.0 including a clearance term out of the peritoneal cavity to account for the absorption of large molecules to the peritoneal tissues, and considering patients who routinely used icodextrin by establishing steady-state plasma concentrations. The model for rats employed a standard three-pore model in which human kinetic parameters were scaled for a rat based on differences in body weight. Both models described the icodextrin molecular weight (MW) distribution as five distinct MW fractions. First order kinetics was applied using degradation rate constants obtained from previous in-vitro measurements using gel permeation chromatography. Ultrafiltration and absorption were predicted during a 4-hour exchange in rats, and 9 and 14-hour exchanges in humans with slow to fast transport characteristics with and without the effect of amylase activity.

♦ Results:

In rats, the icodextrin MW profile shifted towards the low MW fractions due to complete disappearance of the MW fractions greater than 27.5 kDa. Including the effect of amylase activity (60 U/L) resulted in 21.1% increase in ultrafiltration (UF) (7.6 mL vs 6.0 mL) and 7.1% increase in icodextrin absorption (CHO) (62.5% with vs 58.1%). In humans, the shift in MW profile was less pronounced. The fast transport (H) patient absorbed more icodextrin than the slow transport (L) patient during both 14-hour (H: 47.9% vs L: 40.2%) and 9-hour (H: 37.4% vs L: 31.7%) exchanges. While the UF was higher during the longer exchange, it varied modestly among the patient types (14-hour range: 460 – 509 mL vs 9-hour range: 382 – 389 mL). When averaged over all patients, the increases in UF and CHO during the 14-hour exchange due to amylase activity (7 U/L) were 15% and 1.5%, respectively.

♦ Conclusion:

The icodextrin absorption values predicted by the model agreed with those measured in rats and humans to accurately show the increased absorption in rats. Also, the model confirmed the previous suggestions by predicting an increase in UF specific to amylase activity in dialysate, likely due to the added osmolality by the small molecules generated as a result of the degradation process. As expected, this increase was more pronounced in rats than in humans because of higher dialysate concentrations of amylase in rats.     

The microheterogeneity of α1-acid glycoprotein in inflammatory lung disease,cancer of the lung and normal health

The concentration of α₁-acid glycoprotein (AGP, orosomucoid) was measured in sera from 19 patients with primary squamous cell carcinoma of the lung, 16 patients with an inflammatory lung disease and 17 persons with normal health. All sera were further subjected to crossed immuno-affinoelectrophoresis with addition of Con A in the first dimension and sugar in the second dimension. The distribution of AGP into four microheterogeneity forms, which were the result of this analysis, was estimated by measuring the area under the precipitation curve. The microheterogeneity patterns of AGP in the three groups were significantly different from each other (p< 0.001). The total concentration of AGP in the two groups of patients was significantly different from the concentration in the healthy group (p < 0.001).     

Prevention of nosocomial maxillary sinusitis in the ICU: the effects of topically applied α-adrenergic agonists and corticosteroids

Objective We investigated the efficacy of locally applied nasal decongestant agents and corticosteroids for preventing nosocomial maxillary sinusitis in mechanically ventilated patients with multiple trauma. Design and setting A prospective, open-label randomized study in two intensive care units (ICUs). Patients 79 consecutive multiple trauma patients admitted to the ICU who were expected to be mechanically ventilated for more than 3 days. Interventions Patients were randomly assigned to receive either a combination of a locally applied nasal decongestant agents: 2 drops twice/day of xylometazoline nasal solution 0.1% and 100 μg budesonide (NDCA group, n = 39) or placebo (control group, n = 40). Measurements For the diagnosis of radiological maxillary sinusitis patients underwent paranasal computed tomography within 48 h of admission and thereafter every 4–7 days. Infectious maxillary sinusitis was diagnosed by microbiological analysis of fluid aspirated after transnasal puncture of maxillary sinuses. Results Radiological maxillary sinusitis was detected in 54% of patients in the NDCA group (n = 21) but in 82% of controls (p < 0.01), and infectious maxillary sinusitis in 8% of the NDCA group (n = 3) but in 20% of controls (n = 8; p = 0.11). The most common pathogen micro-organisms identified from maxillary aspirates were Acinetobacter (32%) followed by anaerobes (21%). Conclusion Our results indicate that the combination of locally applied xylometazoline hydrochloride and budesonide reduces the incidence of radiological maxillary sinusitis and may reduce also that of nosocomial maxillary sinusitis in mechanically ventilated patients with multiple trauma. Supported by a grant from the Society for Pulmonary and Critical Care Research of East Macedonia and Thrace     

Effects of the α₂-adrenergic agonist clonidine on the pharmacodynamics and pharmacokinetics of 3,4-methylenedioxymethamphetamine in healthy volunteers

The mechanism of action of 3,4-methylenedioxymethamphetamine (MDMA; ecstasy) involves the carrier-mediated and potentially vesicular release of monoamines. We assessed the effects of the sympatholytic α?-adrenergic receptor agonist clonidine (150 μg p.o.), which inhibits the neuronal vesicular release of norepinephrine, on the cardiovascular and psychotropic response to MDMA (125 mg p.o.) in 16 healthy subjects. The study used a randomized, double-blind, placebo-controlled crossover design with four experimental sessions. The administration of clonidine 1 h before MDMA reduced the MDMA-induced increases in plasma norepinephrine concentrations and blood pressure but only to the extent that clonidine lowered norepinephrine levels and blood pressure compared with placebo. Thus, no interaction was found between the cardiovascular effects of the two drugs. Clonidine did not affect the psychotropic effects or pharmacokinetics of MDMA. The lack of an interaction of the effects of clonidine and MDMA indicates that vesicular release of norepinephrine, which is inhibited by clonidine, does not critically contribute to the effects of MDMA in humans. Although clonidine may be used in the treatment of stimulant-induced hypertensive reactions, the present findings do not support a role for α?-adrenergic receptor agonists in the prevention of psychostimulant dependence.     

Assessment of the clinical significance of antigenic and functional levels of α1-proteinase inhibitor (α1-Pi) in infiltrating ductal breast carcinomas

ObjectivesTo determine the clinical significance of α1-proteinase inhibitor (α1-Pi) in infiltrating ductal breast carcinoma patients.Design and methodsSerum levels of α1-Pi, tryptic specific inhibitory capacity and α1-Pi circulating immune complexes were determined using radial immunodiffusion, BAPNA assays and ELISA, respectively. 2-DE-MS and immunohistochemistry were performed to examine α1-Pi protein expression.ResultsA decreased serum level of α1-Pi was found among breast cancer patients in comparison to controls. In addition, we found a significantly decreased mean level of α1-Pi in the node metastatic group when compared to node negative patients. However, the functional activity of the inhibitor did not decrease proportionately. Through 2-DE analyses, a differential expression of α1-Pi isoforms according to tumor stage and node metastatic development was found.ConclusionsBoth α1-Pi levels and specific activity could be a source of complementary clinical information and may provide useful information for a better understanding of the mechanisms of metastasis.     

Advances in the study of the effects of enteric α-defensins on the pathogenesis of inflammatory bowel diseases

防御素作为小肠腺泡底部潘氏细胞分泌的主要抗菌肽,具有广谱的杀菌、抗炎、抗病毒功能,对肠道的黏膜屏障功能和免疫功能都有非常重要的维持和调节作用.近年发现防御素和炎症性肠病(IBD)的发病联系紧密.现将近年来肠源性防御素在IBD发病机制中作用的研究进展进行综述,以期为今后IBD的治疗提供一定的理论依据.     

Dual-targeting of αvβ3 and galectin-1 improves the specificity of paramagnetic/fluorescent liposomes to tumor endothelium in vivo

Molecular imaging of angiogenesis requires a highly specific and efficient contrast agent for targeting activated endothelium. We have previously demonstrated that paramagnetic and fluorescent liposomes functionalized with two angiogenesis-specific ligands, the galectin-1-specific anginex (Anx) and the α(v)β(3) integrin-specific RGD, produce synergistic targeting effect in vitro. In the current study, we applied Anx and RGD dual-conjugated liposomes (Anx/RGD-L) for angiogenesis-specific MRI in vivo, focusing on the specificity and efficacy of liposome association with tumor endothelium. The targeting properties, clearance kinetics and biodistribution of Anx/RGD-L were investigated in B16F10 melanoma-bearing mice, and compared to liposomes functionalized with either Anx (Anx-L) or RGD (RGD-L). The contrast enhancement produced by dual- and single-targeted nanoparticles in the tumor was measured using in vivo T(1)-weighted MRI, complemented by ex vivo immunohistochemical evaluation of tumor tissues. Blood clearance kinetics of Anx/RGD-L was three-fold more rapid than for RGD-L, but comparable to Anx-L. Both dual- and single-targeted liposomes produced similar changes in MRI contrast parameters in tumors with high inter-tumor variability (ΔR(1)=0.04±0.03s(-1), 24h post-contrast). Importantly, however, the specificity of Anx/RGD-L association with tumor endothelium of 53±6%, assessed by fluorescence microscopy, was significantly higher compared to 43±9% (P=0.043) and 28±8% (P=0.0001) of Anx-L and RGD-L, respectively. In contrast, long-circulating RGD-L were on average 16% more efficient in targeting tumor endothelium compared to Anx/RGD-L. Significant differences were also found in the biodistribution of investigated contrast agents. In conclusion, synergistic targeting of α(v)β(3) and galectin-1 improved the specificity of the association of the liposomal contrast agent to tumor endothelium in vivo, providing therefore a more reliable MRI readout of the angiogenic activity.     

The rearrangement and amplification of C-erbB-1 gene in the development of MDS and their clinical significance in diagnoses and prognoses

In order to explore whether the rearrangement and amplification of C-erbB-l gene were associatedwith the development of MDS and their clinicalsignificance in diagnoses and prognoses. digitoxin-labelled oligonucleotide probes were used to detect 33     

Peripheral α-adrenoreceptors are involved in the development of capsaicin induced ongoing and stimulus evoked pain in humans

While the sympathetic nervous system seems to be involved in some pain states, the mechanisms linking the sensory and sympathetic nervous system are unclear. In this study the possible involvement of peripheral α-adrenoreceptors in the development of capsaicin induced ongoing pain and mechanical hypersensitivity was examined in humans. Intradermal capsaicin injections in the volar aspect of the arm gave rise to ongoing burning pain and dysesthesia as well as mechanical hypersensitivity. Ongoing pain and pain evoked by von Frey filament stimulation was rated on a numerical rating scale after intradermal capsaicin injection. The area of skin in which von Frey filament stimulation evoked pain was measured. A subcutaneous injection of phentolamine (α-adrenoreceptor antagonist) on one side and saline on the other side prior to the capsaicin injection was done to evaluate the role of the peripheral α-adrenoreceptors in development of capsaicin induced sensory symptoms and signs. Significantly less ongoing and evoked pain developed on the phentolamine injected side compared to the saline side, the latter in the area adjacent to the capsaicin injection (primary zone) and well outside the area of flare (secondary zone). The area in which pain could be evoked on the phentolamine injected side was restricted to the area of flare and was significantly smaller than on the saline injected side. Mechanical stimulation gave rise to aftersensation and radiation of pain on the saline injected side in all subjects but only in one case on the phentolamine injected side. Peripheral α-adrenoreceptors thus seem to be involved in functional changes of primary afferents which contribute to ongoing pain and mechanical stimulus evoked pain.     

d-Psicose Inhibits Intestinal α-Glucosidase and Suppresses the Glycemic Response after Ingestion of Carbohydrates in Rats

d-psicose is one of the rare sugars present in small quantities in commercial carbohydrates and agricultural products. In this study, we investigated the effects of d-psicose on the activities of α-amylases and α-glucosidases in vitro, and evaluated the effects of d-psicose on the in vivo postprandial glycemic response using rats. In the in vitro study, d-psicose potently inhibited the intestinal sucrase and maltase, however, slightly inhibited the intestinal and salivary α-amylase activities. Male Wistar rats (6 months old) were administrated 2 g/kg of sucrose, maltose or soluble starch together with 0.2 g/kg of d-psicose or d-fructose. The d-psicose significantly inhibited the increment of plasma glucose concentration induced by sucrose or maltose. The starch-induced glycemic response tended to be suppressed by d-psicose, however the suppression was not significant. These results suggest that d-psicose inhibits intestinal sucrase and maltase activities and suppresses the plasma glucose increase the normally occurs after sucrose and maltose ingestion. Thus, d-psicose may be useful in preventing postprandial hyperglycemia in diabetic patients when foods containing sucrose and maltose are ingested.     

Efficacy and safety of antioxidant treatment with α-lipoic acid over 4 years in diabetic polyneuropathy: the NATHAN 1 trial

OBJECTIVE

To evaluate the efficacy and safety of α-lipoic acid (ALA) over 4 years in mild-to-moderate diabetic distal symmetric sensorimotor polyneuropathy (DSPN).

RESEARCH DESIGN AND METHODS

In a multicenter randomized double-blind parallel-group trial, 460 diabetic patients with mild-to-moderate DSPN were randomly assigned to oral treatment with 600 mg ALA once daily (n = 233) or placebo (n = 227) for 4 years. Primary end point was a composite score (Neuropathy Impairment Score [NIS]–Lower Limbs [NIS-LL] and seven neurophysiologic tests). Secondary outcome measures included NIS, NIS-LL, nerve conduction, and quantitative sensory tests (QSTs).

RESULTS

Change in primary end point from baseline to 4 years showed no significant difference between treatment groups (P = 0.105). Change from baseline was significantly better with ALA than placebo for NIS (P = 0.028), NIS-LL (P = 0.05), and NIS-LL muscular weakness subscore (P = 0.045). More patients showed a clinically meaningful improvement and fewer showed progression of NIS (P = 0.013) and NIS-LL (P = 0.025) with ALA than with placebo. Nerve conduction and QST results did not significantly worsen with placebo. Global assessment of treatment tolerability and discontinuations due to lack of tolerability did not differ between the groups. The rates of serious adverse events were higher on ALA (38.1%) than on placebo (28.0%).

CONCLUSIONS

Four-year treatment with ALA in mild-to-moderate DSPN did not influence the primary composite end point but resulted in a clinically meaningful improvement and prevention of progression of neuropathic impairments and was well tolerated. Because the primary composite end point did not deteriorate significantly in placebo-treated subjects, secondary prevention of its progression by ALA according to the trial design was not feasible.Diabetic distal symmetric sensorimotor polyneuropathy (DSPN) is a chronic progressive disease affecting around one-third of the diabetic population and accounts for considerable morbidity, increased mortality, and reduced quality of life (1,2). Recent long-term studies in type 2 diabetic patients indicate that the current strategies of intensive diabetes therapy or multifactorial cardiovascular risk intervention are not sufficient to slow the progression of DSPN (3–5). Thus, effective treatment of DSPN remains challenging for the physician (1,6).Based on the pathogenetic mechanisms of DSPN, potential disease-modifying therapeutic approaches have been developed including antioxidants such as α-lipoic acid (ALA) (7–9) to diminish increased oxidative stress (10). Other potential modalities include the aldose reductase inhibitors (11), growth factors (12), and the protein kinase C-β inhibitor ruboxistaurin (13). These drugs have been designed to favorably influence the underlying pathophysiology of the disorder rather than for symptomatic pain relief. However, several problems have been encountered previously in designing appropriate clinical trials in DSPN. Among these, the most important are as follows: 1) the lack of homogeneity of patients studied with respect to both the form of neuropathy and the degree of glycemic control; 2) different pathogenetic pathways, the relative importance of which may vary intraindividually; 3) stages of neuropathy that are too advanced; 4) the use of end points with rather large variability between individuals and between centers; 5) the unknown relevance of end points used; and 6) study durations too short to allow for a favorable functional or structural effect (6,14,15).Treatment with ALA administered intravenously or orally for several weeks or months improves neuropathic symptoms and deficits (7–9). However, based on the assumption that a therapeutic agent may prevent worsening of DSPN but not cause improvement, clinical trials should be conducted for a minimum period of 3 years to achieve a clinically meaningful change of two Neuropathy Impairment Score (NIS) points (16,17). Therefore, we assessed the efficacy and safety of oral treatment with 600 mg ALA once daily in mild-to-moderate DSPN.     

The role of hepatic liver X receptor α- and sterol regulatory element binding protein-1c-mediated lipid disorder in the pathogenesis of non-alcoholic steatohepatitis in rats

Liver X receptor α (LXRα) and sterol regulatory element binding protein-1c (SREBP-1c) were studied in rats with non-alcoholic steatohepatitis (NASH) induced by a high-fat diet. Forty 5-week-old rats were fed either a high-fat diet (n = 30) or a normal diet (n = 10) for 9, 13 or 17 weeks. The mRNA and protein levels for LXRα and SREBP-1c were measured at each time point, as was fatty acid synthase (FAS) activity and the serum levels of free fatty acid (FFA) and triglyceride (TG). The mRNA and protein levels for LXRα and SREBP-1c, FAS activity and serum levels of FFA and TG all significantly increased from week 9 in the high-fat diet rats versus controls. In conclusion, a high-fat diet upregulates LXRα which, in turn, upregulates SREBP-1c, increasing the activity of FAS and FFA and accumulation of TG in hepatocytes. Thus, LXRα and SREBP-1c contribute to the development of NASH.     

Behavioral characterization of knockin mice with mutations M287L and Q266I in the glycine receptor α1 subunit

We used behavioral pharmacology to characterize heterozygous knockin mice with mutations (Q266I or M287L) in the α1 subunit of the glycine receptor (GlyR) (J Pharmacol Exp Ther 340:304-316, 2012). These mutations were designed to reduce (M287L) or eliminate (Q266I) ethanol potentiation of GlyR function. We asked which behavioral effects of ethanol would be reduced more in the Q266I mutant than the M287L and found rotarod ataxia to be the behavior that fulfilled this criterion. Compared with controls, the mutant mice also differed in ethanol consumption, ethanol-stimulated startle response, signs of acute physical dependence, and duration of loss of righting response produced by ethanol, butanol, ketamine, pentobarbital, and flurazepam. Some of these behavioral changes were mimicked in wild-type mice by acute injections of low, subconvulsive doses of strychnine. Both mutants showed increased acoustic startle response and increased sensitivity to strychnine seizures. Thus, in addition to reducing ethanol action on the GlyRs, these mutations reduced glycinergic inhibition, which may also alter sensitivity to GABAergic drugs.     

Biomarkers in the prognostic evaluation of ischemic stroke: Is there benefit in the measurements of TREM-1 and TREM-2 in the acute phase?

Background and purposeTriggering receptors expressed on myeloid cells 1 and 2 (TREM-1 and TREM-2) are cell surface receptors important for modulation of microglia immune response. In this study, we evaluate serum levels of TREM-1 and TREM-2 as potential biomarkers in acute ischemic stroke (AIS).Material and methodsProspective cohort study of 50 patients with AIS admitted at our hospital. Serum TREM-1 and TREM-2 was evaluated within 24 h of the acute event and on the third and fifth days after the stroke. Neurological stroke severity and global disability were determined with the National Institutes of Health Stroke Scale (NIHSS) and modified Rankin Scale (mRS) at the same three times and at the time of hospital discharge.ResultsTREM-1 and TREM-2 levels were elevated in stroke. TREM-1, but not TREM-2, exhibited correlations with NIHSS and mRS within 24 h (NIHSS and TREM-1: r_S = 0.31, p = 0.029; mRS and TREM-1: r_S = 0.32, p = 0.023). The serum level of TREM-1 within 24 h correlated with the neurological outcomes at hospital discharge (NIHSS and TREM-1: p = 0.021; mRS and TREM-1: p = 0.049). The serum concentrations of TREM-1 protein within 24 h after stroke was significantly higher in patients with poor outcome (mRS > 2) at hospital discharge (p = 0.021). After Exact Logistic Regression, large segmental stroke (O.R. = 4.14; 95CI = 1.07–16.09; p = 0.040) and initial sTREM levels (O.R. = 1.02; 95CI 1.00–1.04; p = 0.045) remained independent prognostic factors for AIS poor outcome (mRS > 2).ConclusionIn our study, TREM-1 and TREM-2 were significantly increased in AIS. Early elevation of TREM-1 correlated with stroke severity and it was an independent prognostic factor for stroke outcome.     

Activation of Sphingosine-1-Phosphate Receptor 1 in the Spinal Cord Produces Mechanohypersensitivity Through the Activation of Inflammasome and IL-1β Pathway

Sphingosine-1-phosphate (S1P) receptor 1 subtype (S1PR1) activation by its ligand S1P in the dorsal horn of the spinal cord causes mechanohypersensitivity. The cellular and molecular pathways remain poorly understood. We report that the activation of S1PR1 with an intrathecal injection of the highly selective S1PR1 agonist SEW2871 led to the development of mechanoallodynia by activating the nod-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome (increased expression of NLRP3, cleaved caspase 1 and mature IL-1β) in the dorsal horn of the spinal cord. The functional S1PR1 antagonist FTY720 blocked NLRP3 activation and IL-1β production. Moreover, inhibiting IL-10 signaling with an intrathecal injection of an anti–IL-10 antibody attenuated the beneficial effects exerted by FTY720. This finding suggests that disrupting S1PR1 signaling engages beneficial IL-10–dependent pathways. Notably, we found that mice with astrocyte-specific deletions of S1pr1 did not develop mechanoallodynia after intrathecal injection of SEW2871 and exhibited decreased levels of cleaved caspase 1, identifying astrocytes as a key cellular locus for S1PR1 activity. Our findings provide novel mechanistic insights on how S1PR1 activation in the spinal cord contributes to the development of nociception while identifying the cellular substrate for these activities.PerspectiveThis study is the first to link the activation of NLRP3 and IL-1β signaling in the spinal cord and S1PR1 signaling in astrocytes to the development of S1PR1-evoked mechanoallodynia. These findings provide critical basic science insights to support the development of therapies targeted toward S1PR1.     

Fetal death associated with the use of 3,4-MDPHP and α-PHP

Introduction: The second largest group of new drugs monitored by the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) is synthetic cathinones. Substances that are controlled by the law are immediately replaced by new uncontrolled derivatives that cause constant and dynamic changes on the drug market. Some of the most recent synthetic cathinones that have appeared on the “legal highs” market are 3,4-methylenedioxy-α-pyrrolidinohexanophenone (3,4-MDPHP) and α-pyrrolidinohexanophenone (α-PHP).

Case history: A 21-year-old woman in the 36th week of pregnancy presented with psychomotor agitation. Fetal demise was demonstrated and a caesarean delivery performed.

Methods: The analyses were carried out by liquid chromatography with mass spectrometry (LC–MS/MS). The analytes were isolated from the biological material by liquid–liquid extraction with n-butyl chloride.

Results: 3,4-MDPHP and α-PHP were detected and quantified in both the fetus’ and the mothers blood, as well as in the mothers urine samples. The determined concentrations of 3,4-MDPHP and α-PHP were, 76?ng/mL and 12?ng/mL in the fetal blood sample, 16?ng/mL and traces in the mothers blood, and 697?mg/mL and 136?ng/mL in the mothers urine, respectively.

Discussion: The presented case demonstrates that 3,4-MDPHP and α-PHP transfers from maternal blood to fetal blood. Blood concentrations of these compounds were higher in the fetus than in the mother. Based on the known effects of these substances and the patient’s presentation and clinical course, it would seem that these substances contributed to the fetal death.

Conclusions: The detected substances transfer from maternal to fetal circulation, and synthetic cathinone blood concentration can be higher in the fetus than in the mother. This along with the fact immature metabolic ability makes a fetus more vulnerable to cathinones intoxication than adults.